285 tires=? gear ratio

[BApple]

I plan on putting 285 tires on my new CTD. My truck will have 3. 73 gears. What gear ratio will the 285 tire take me to? Thanks.

 

[jrikli]

285's

Good question. 1) Anyone with a 555 measured their mpgs with the 285 tire change? 2) Where can you find them, I'm looking for a 285 road tire with no results. 3) We should be able to run at 75 without the harmonic rumble, right? Thanks for the help... .

 

[fishjack1]

Check out the links at the bottom of this page and you should find what your looking for:



http://www.dodgeram.org/tech/specs/axle/rpm_vs_mph.htm

 

[klenger]

Changing your tires does not change the gear ratio, only the effective gear ratio. If you have excel, you can put the numbers into the spreadsheet at the link below to see how the change in tire size will affect RPM's and speed.



http://www.klenger.net/dodge/general-reference/gear-speed-calculator.xls

 

[BApple]

Thanks, I think I figured it out. 285's with 3. 73 would take my EFFECTIVE ratio to 3. 60. Guess I should have clarified effective, what other kind is there

 

[zachv]

Non-effective??Oo.

 

[gsbrockman]

Originally posted by BApple

Thanks, I think I figured it out. 285's with 3. 73 would take my EFFECTIVE ratio to 3. 60. Guess I should have clarified effective, what other kind is there

That's almost the same reduction I had with my '00 Dodge 2500 Quad Cab CTD with auto and 3. 55 axle when I went from stock LT265/75R16's to LT285/75R16's in the Bridgestone Dueler A/T REVO's. (My effective ratio went from 3. 55 to 3. 42). Talk about an interstate cruiser !

Greg

 

[Fitasc]

BAPPLE--



Remember to have your speedo re calibrated w/ the 285's. you will need to use 634 revolutions per mile to achieve an accurate adjustment. The actual # is: 633. 85, which is not programmable @

most dealers. ( takes about 2 minutes)



When you do the swap you may want to consider buying a 5th tire for your spare. The factory 265 is worthless if you need to use the spare, unless you are 4x2 and use the smaller diameter on the front.....



JAH